The RD48 (ROSE) collaboration has succeeded to develop radiation hard silicon detectors, capable to withstand the harsh hadron fluences in the tracking areas of LHC experiments. In order to reach ...this objective, a defect engineering technique was employed resulting in the development of Oxygen enriched FZ silicon (DOFZ), ensuring the necessary O-enrichment of about 2×10
17 O/cm
3 in the normal detector processing. Systematic investigations have been carried out on various standard and oxygenated silicon diodes with neutron, proton and pion irradiation up to a fluence of 5×10
14
cm
−2 (1
MeV neutron equivalent). Major focus is on the changes of the effective doping concentration (depletion voltage). Other aspects (reverse current, charge collection) are covered too and the appreciable benefits obtained with DOFZ silicon in radiation tolerance for charged hadrons are outlined. The results are reliably described by the “Hamburg model”: its application to LHC experimental conditions is shown, demonstrating the superiority of the defect engineered silicon. Microscopic aspects of damage effects are also discussed, including differences due to charged and neutral hadron irradiation.
p-spray isolation of double-sided detectors is investigated by computer simulations and measurements on full-size detector prototypes. Simulations showed that a B p-spray implant doses 4/spl ...middot/10/sup 12/, 6/spl middot/10/sup 12/, and 8/spl middot/10/sup 12/ cm/sup -2/ and implant energy 60 keV would yield breakdown voltages above 200 V for unirradiated detectors with oxide charge 2/spl middot/10/sup 11/ cm/sup -2/. The simulations showed that the breakdown voltage decreases with increasing p-spray dose. According to the computer simulations, the detectors should perform equally well after irradiation giving an oxide charge of 1/spl middot/10/sup 12/ cm/sup -2/. HERA-B strip detectors with p-spray isolation were manufactured, using the three simulated doses. The average breakdown voltages and standard deviations were 167/spl plusmn/31 V for the 4/spl middot/10/sup 12/ cm/sup -2/ dose, 151/spl plusmn/16 V for the 6/spl middot/10/sup 12/ cm/sup -2/ dose, and 127/spl plusmn/13 V for the 8/spl middot/10/sup 12/ cm/sup -2/ dose. The measured decrease in breakdown voltage is in good agreement with the computer simulations.
HERA-B detectors with p-spray isolation on the N-side; unirradiated results Schjolberg-Henriksen, K.; Westgaard, T.; Sundby Avset, B.
1999 IEEE Nuclear Science Symposium. Conference Record. 1999 Nuclear Science Symposium and Medical Imaging Conference (Cat. No.99CH37019),
1999, Letnik:
1
Conference Proceeding
P-spray isolation of double-sided detectors is investigated by computer simulations and measurements on full-size detector prototypes. Simulations showed that boron p-spray implant doses 4.10/sup ...12/, 6.10/sup 12/, and 8.10/sup 12/ cm/sup -2/ and implant energy 60 keV would yield breakdown voltages above 200 V for unirradiated detectors with oxide charge 2.10/sup 11/ cm/sup -2/. The simulations showed that the breakdown voltage decreases with increasing p-spray dose. According to the computer simulations, the detectors should perform equally well after irradiation giving an oxide charge of 1.10/sup 12/ cm/sup -2/. HERA-B strip detectors with p-spray isolation were manufactured, using the three simulated doses. The average breakdown voltages and standard deviations were 167/spl plusmn/31 V for the 4.10/sup 12/ cm/sup -2/ dose, 151/spl plusmn/16 V for the 6.10/sup 12/ cm/sup -2/ dose, and 127/spl plusmn/13 V for the 8.10/sup 12/ cm/sup -2/ dose. The measured decrease in breakdown voltage is in good agreement with the computer simulations.
Measurements on a hole trap in neutron-irradiated silicon Avset, Berit Sundby
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/1997, Letnik:
388, Številka:
3
Journal Article
Recenzirano
High resistivity n-type Si has been neutron irradiated and characterized by Deep Level Transient Spectroscopy (DLTS). In addition to common irradiation induced traps we have observed a hole trap with ...activation energy around 0.475 eV. For characterizing the trap we have observed the DLTS signal versus filling pulse bias combined with simulations of carrier concentrations. According to these measurements, the capture cross section is very small for holes as well as for electrons; of the order of 10
−18–10
−20 cm
2. The hole capture cross section is temperature dependent in the temperature range covered.
The performance and stability of silicon diode detectors can be improved by implementing guard ring structures around the active detector area. The purpose of this work is to study design parameters ...influencing the performance of multiguard structures, especially the effect of metal field plates. An important feature is the potential distribution in the multiguard ring structure which depends on the bulk doping concentration, the oxide charge, the size of the gap between guard rings and the field-plate design. We have made a systematic investigation of the effect of distance between floating p
+ guard rings with two different metal field plate designs. We have also varied the width of the field plates and studied the effect of gamma irradiation. Numerical simulations have been done to compare with results from the experimental potential distributions between guard rings.
Phosphorus-doped high-resistivity silicon from different vendors and production series has been used to fabricate diodes in the same process run. The diodes were investigated by capacitance-voltage, ...current-voltage and deep level transient spectroscopy (DLTS) measurements with the intention to evaluate the quality variation of silicon diodes due to the starting material. The leakage current measurements showed that the average leakage current at full depletion was ∼ 5 times larger in the worst wafer compared to the best. The wafers were divided into two batches which received two different segregation annealings. It was observed that the improvement in the average leakage current due to long versus short segregation annealing varied substantially between wafers.
Recent detector developments at SINTEF (industrial presentation) Sundby Avset, Berit; Evensen, Lars; Uri Jensen, Geir ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/1998, Letnik:
409, Številka:
1-3
Journal Article
Recenzirano
Results from SINTEF's research on radiation hardness of silicon detectors, thin silicon detectors, silicon drift devices, reach-through avalanche photodiodes, and detectors with thin dead layers are ...presented.
